First things first - the error you are getting is due to the fact that the Administrator role ID in your SecurityConfig configuration file does not match the one in the database. This usually happens when you try to connect two solutions to the same database without making sure they have the same configurations.
Regarding the question you have posted - it is possible to have multiple solutions hooked up to a single database instance. For this purpose you will need to use Sitefinity's Load Balancing
. Please go through the documentation for further reference.
It is also possible to sync between solutions as well. For this purpose you can take advantage of Sitefinity's Site Synchronization module. More information is also in our Documentation
Ivan D. Dimitrov
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